During the first few years of the colour-ringing project, the numbers of successful breeding Stonechats on Dersingham Bog had been quite low, with 5 pairs and 10 juveniles as a maximum. However, in 2015, we saw a big increase in the numbers when 10 pairs produced 51 ringed juveniles from 18 nests. It was more than the combined total of the previous three years.
But surely we were at saturation point and there wasn’t room on the reserve for any more pairs? Apparently no one had told the Stonechats that it was a full house as 2016’s breeding season surpassed anything we could have expected. Our Stonechats managed to squeeze a further 3 territories onto the reserve, bringing the number of pairs that year to 13 and the total number of juveniles ringed climbed to an amazing 95.
With such intense monitoring efforts by our volunteers, we were pretty confident that we’d found ALL the nests of the known pairs. However, there was one that got away, with a late first brood by an unknown pair found already fledged in an isolated and very wet area of the mire. Over this 2016 season 30 nests were found in total, with 5 of those being known failures.
Some pairs made three nesting attempts, although only one pair managed to fledge all three broods. That female is one of our most prolific breeders and it’s now her third year of nesting on the reserve and it’ll be interesting to see if she returns next year. She’s currently still on her territory on the reserve and seems paired with a new ringed male. The other pairs that attempted three nests had experienced earlier failures, either in their first or second attempts so the rest of the pairs were only able to bring off two broods in total.
Have we reached saturation point on the reserve or is there still space for more pairs on fresh territories? We’ve been surprised at how close some of the neighbouring territories have been so we’ve given up predicting there’s no more ‘room at the inn.’
And ringing 95 juveniles this year may have been an amazing number but it did feel a bit like getting out on 99 at cricket when we didn’t reach the 100, and we were confident we hadn’t missed any.
Will next year break that barrier? And if they do, can our nest-finding volunteers can cope?!